Hybrid vehicle systems typically utilize one or more electric, permanent magnet motors as part of a transmission system that provides a propulsion source to compliment the engine. The accuracy of the manufacture, service, and operation of these motors to produce specified torque profiles is important to the consistent and efficient operation of the vehicle.
Various issues can arise in the manufacture, assembly, transport, service, and use of the motors that can affect the performance. For example, the magnet flux strength of the motors can be diminished due to factors such as the particular characteristics of the magnets, including field strength and effects of heat and vibration. Similarly, if the stators of the motors are not properly wound with the specified number of turns per coil, performance can be affected. Another factor that contributes to the performance of the motors is the material utilized to fabricate the stators of the motors. Typically, steel or a similar material forms part of the magnetic circuit through with the magnet flux of the motor flows. As an example, the magnetic permeability of the steel can vary with the types of material used to manufacture the motors, and this variation can impact the performance of the motor.
One mechanism of evaluating a motor involves the calculation and evaluation of a voltage constant, which is a function of the number of windings of the stator, the permeability of the flux path, and the field strength of the rotor magnets. Conventional methods calculate the voltage constant of the motor based on voltage measurements from the motor itself. However, these methods are typically unavailable when the motor is installed in the transmission.
Accordingly, it is desirable to provide methods for evaluating permanent magnet motors in transmissions in a variety of situations, such as during operation, after manufacturing or during service of the vehicle. In addition, it is desirable to provide such methods in an economical and convenient manner. Furthermore, other desirable features and characteristics of the present invention will become apparent from the subsequent detailed description and the appended claims, taken in conjunction with the accompanying drawings and the foregoing technical field and background.